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PRACTICAL ORGANIC CHEMISTRY

nitrate, it is undesirable to let the precipitate become quite dry.
The various reactions described below are carried out witli
the slightly moist and well pressed precipitate.

Properties.—Colourless needles; soluble in water and
methyl alcohol ; slightly soluble in ethyl alcohol.
Reactions.—The following reactions are performed in test-
tubes with about a gram of the substance.
1.  Warm  the  substance with a few  c.c.  of ethyl  alcoliol.
Vigorous effervescence occurs and the liquid turns red.    Wlieii
effervescence ceases, add water.   An oil separates out on   tlie
surface consisting of benzene mixed with a little phenetol.
C0H5N0SO4H + C2H6O = C6HG + N2 + C2H4O + H9SO4
C0H3N3SO4H + C2H(JO = C6H5OC2H5 + N2 + H2SO4.
2.   Dissolve about a gram of the substance in a little water,
cool in  ice  and  make alkaline with  caustic  soda.    Make    an
alkaline solution of stannotts hydrate by dissolving 3—4 grams
of stannous chloride in twice its weight of water and adding'
strong caustic soda  solution  until the  precipitate redissolves.
Cool the diazo solution and add the alkaline stannous hydrate.
Effervescence occurs, nitrogen is liberated and benzene separates
on the surface of the liquid and can be detected by its smell.
C6H5N2. ONa + Sn(ONa)2 -I- HaO = C6Ha + N2 + Na2SnO:} + NaO 1I -
3.   Dissolve the substance in a few c.c. of cold water and axld
a solution of bromine in  potassium bromide  until  no  furtlier
turbidity is produced.    A black oil collects at the bottom of  the
test-tube.    Pour off the top layer as far as possible, and let   the
oil stand in cold water.   It .solidifies.   This is the perbromide of
diazobenzene.
C6H5N2SO,H + KBr + Br2=C0H5NBrNBr2 + KHSO4.
Decant any liquid and warm the perbromide with a little alcoliol.
Nitrggen and bromine are given off and bromobenzene is
formed.
CfcHfiNBrNBr2 = C6H5Br + N2 + Bi>
4.    Dissolve the  substance in a little  cold water and    add